"Investigators extensively combed the remnants of the building, conducted interviews and presented evidence to forensic laboratories for analysis," Minneapolis police said in a statement. "Despite this thorough investigation, the cause of the blaze cannot be determined, although arson investigators have ruled out suspicious circumstances."

The building housed McMahon's Pub and six upstairs apartments. McMahon's bartender Ryan Richner, 25, died in the fire, along with five people staying with him in his apartment: Annie Gervais, 43, her son Andrew Gervais, 26, and his three children, 3-year-old twins Alicia and Austin, and 2-year-old Colton.